Leighton Meester dating Adam Brody

The couple - who co-starred in 2011 romantic-comedy movie 'The Oranges' - have reportedly been secretly seeing each other for several weeks, which comes after they used to "hang out" together while shooting the film.

An insider confirmed to Us Weekly: "They were always close and friendly."

The 26-year-old beauty - who is known for her role as Blair Waldorf in teen drama TV series 'Gossip Girl' - and the 33-year-old actor were spotted "hugging and laughing" as they took in art exhibitions at the Los Angeles County Museum of Art earlier this month.

Leighton and Adam - who starred as Seth Cohen in US teen drama TV series 'The O.C.' for four years - also travelled to Bangkok together earlier this year where they were spotted at the Siam Kempinski Hotel in the Thai capital city.

Adam was recently linked to 34-year-old director Lorene Scafaria - who helmed Steve Carell and Keira Knightley's comedy-drama movie 'Seeking a Friend for the End of the World' - while Leighton has previously dated 'Austin Powers' actor Aaron Himelstein.